The last official letter written by Princess Diana three weeks before she died is expected to be sold for £3,000 at auction in Birmingham.

The letter, which is on Kensington Palace headed note paper, was sent to humanitarian campaigner Dilys Cheetham.

The Princess of Wales thanks Mrs Cheetham for delivering aid to refugee camps in the Mostar area of Bosnia.

The note, which is hand signed and dated 11 August 1997, will be sold at Fellows Auctioneers on Monday.

The letter was written after Princess Diana had returned from visiting Bosnia as part of her campaign to help landmine victims.

She died on 31 August 1997 in a car crash in Paris.

The letter says: "I could not help but be deeply moved by the experience which hardened my resolve to ensure that the world does not forget that those who have been so needlessly maimed by these terrible weapons will need care and support for many years to come."

Image copyrightPAImage caption
Princess Diana died on 31 August 1997 in a car crash in Paris

The note was originally sold by Mrs Cheetham in a charity auction in 1999 and bought by celebrity photographer Jason Fraser.

He sold it to a private British collector in 2007 on the 10th anniversary of her death.